These are exciting times for Jaguar, remarkably so given how recently their Tata owners were seeking a substantial injection of capital from the British Government. Jaguar Land Rover have turned around their business in very short order, producing more than £200m in profit per quarter in 2010.

So perhaps it shouldn’t come as a surprise to see Jaguar launch the fastest, most powerful and most expensive series production model in the brand’s history, the 542 bhp XKR-S.

For the first time with a series production car, Jaguar gains entry to the exclusive ‘300kph club’ thanks to the effortless performance of the XKR-S’s supercharged 5.0-litre AJ-V8 engine. A revised fuelling map means the direct-injection powerplant now produces 542bhp and 680Nm of torque, contributing to a 0-60mph time of 4.2 seconds. The Performance active exhaust encourages and rewards the enthusiastic driver with dramatic, motorsport-inspired aural feedback.

The XKR-S is not merely the quickest Jaguar ever but also the most agile, responsive and driver-focused. The pinnacle of the XK range builds on feedback gathered from the supercharged XKR and has been developed to extend the performance parameters of the car. This new harder-edged character allows the enthusiastic driver to explore the outer limits of the car’s dynamics without losing the refinement and usability for which Jaguar is famous.

Styling – more aggression but less style..

Whilst many of the design updates on the XKR-S are functional in nature (rear spoiler, side intakes and carbon-fibre splitter) I can’t help wishing they’d managed to integrate them more into the core XK styling – as Ferrari were able to achieve with the underfloor aerodynamic design of the F430 and 458 Italia.

Ian Callum, Design Director, Jaguar Cars said: “The styling of this car isn’t about image, it’s about true performance. Like other iconic Jaguars before it, the styling has been driven by geometry and aerodynamics for genuine design purity. The physics required to achieve 300kph have led the aesthetic; if you don’t like the way it looks, you probably won’t like the way it drives either.”

Fair enough. There’s a certain counter-intuitive appeal in equating ‘ugly’ with ‘fast’, not to say the XKR-S is without its visual appeal, but customers who spend £100,000 or more on a car like to feel they’re buying something unique rather than a tuned-up base model.

The necessary revisions were made after extensive Computational Fluid Dynamics work, proven through wind tunnel testing and include slimmer LED headlights, a more compact main air intake and vertical side power vents. The XKR-S aerodynamic modifications have contributed to an overall reduction in lift of 26 per cent. In order to balance front and rear lift, the XKR-S features a separate carbon-fibre rear wing, a first for the XK range, which works in concert with the similarly constructed Venturi structure underneath the rear bumper.

The assertive new appearance of the XKR-S is subtly highlighted by some carefully chosen details exclusive to this model. Exterior trim is finished in gloss black, complemented by 20-inch Vulcan lightweight forged alloys in a dark technical finish.

The XKR-S is available in a range of five paint colours, two of which evoke Jaguar’s competition heritage: Italian Racing Red and French Racing Blue.

Like the lining of a bespoke suit, the finishing touch is provided by the brake calipers, available in either red or gunmetal and emblazoned with the ‘Jaguar’ name.

Handling – b-road precision instrument

This fundamental strength of the XK’s aluminium platform allowed Jaguar’s Vehicle Integrity team, led by Mike Cross, to develop the dynamic attributes of the XKR-S to the full, without affecting refinement. Taking the solid foundation of the base XK as a starting point, both front and rear suspension systems have been upgraded.

The double wishbone front suspension has been comprehensively revised with a new aluminium steering knuckle that significantly increases camber and castor stiffness has transformed the accuracy and weighting of the steering for greater levels of connection, feedback and precision. The Active Differential Control has been reprogrammed to reduce steering sensitivity at the very high speeds of which the car is capable, increasing stability and driver control.

Rear suspension geometry has been revised with rear wheel steer optimised for maximum agility while spring rates have been increased at both ends of the car by 28 per cent. Bespoke software for Jaguar’s Adaptive Damping has been written for the XKR-S, ensuring both total body control and maximum traction and grip.

The XKR-S is equipped as standard with Jaguar’s High Performance Braking System. Lighter and more powerful, this features cast iron and part aluminium monobloc calipers for a combination of power, stability and feel. The brake discs – measuring 380mm at the front and 376mm at the rear – are internally ventilated to provide repeated, fade-free stopping power.

In combination with pad surface increases of 44 per cent front and 31 per cent rear the system provides total security and confidence on both road and track, shown most clearly by the XKR-S’s stopping distance which from 124mph has been improved by 2.7 per cent over the already impressive XKR.

Interior

The interior of the XKR-S has been subtly upgraded over the XKR to suit its new hardcore purpose. Exclusive to the XKR-S are the new Performance front seats with an integrated head restraints and increased lateral and squab support to hold driver and passenger securely and comfortably in place during the high speed cornering of which this car is capable. The 16-way adjustment of squab, cushion, lumbar and bolster elements is supplemented by memory and heating functions.

A new leather-wrapped, multi-function steering wheel has also been added, providing a beautiful, tactile interface between car and driver as do the bright, Jaguar-embossed, stainless steel pedals.

New trim materials are available including ebony soft-feel paint for the switches and gloss black finish to the centre console, carbon leather accents cover the seats, featuring unique contrast micro-piping and stitching combinations in Reims Blue, Red and Ivory.

At £97,000 the XKR-S’s performance had better be good, and it is, so perhaps its best to look beyond its looks and just enjoy the way it drives.